/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 姚东名
 * Date: 2024-10-05
 * Time: 14:08
 */
public class HashBuck2<K, V> {
    static class Node<K, V> {
        public K key;
        public V val;
        public Node<K, V> next;

        public Node(K key, V val) {
            this.key = key;
            this.val = val;
        }
    }

    public Node<K, V>[] array = (Node<K, V>[]) new Node[10];
    public int usedSize;
    public static final double DEFAULT_LOAD_FACTOR = 0.75f;

    //插入数据
    public void put(K key, V val) {
        int hash = key.hashCode();
        int index = hash % array.length;
        Node<K, V> cur = array[index];
        while (cur != null) {
            if (cur.key.equals(key)) {
                cur.val = val;
                return;
            }
            cur = cur.next;
        }
        Node<K, V> node = new Node<>(key, val);
        //进行尾插
        node.next = array[index];
        array[index] = node;
        usedSize++;
        //判断负载因子是否超过指定的数值
        if (doLoadFactor() > DEFAULT_LOAD_FACTOR) {
            //进行扩容
            resize();
        }
    }

    private void resize() {
        Node<K, V>[] newArray = (Node<K, V>[]) new Node[array.length * 2];
        for (int i = 0; i < array.length; i++) {
            Node<K, V> cur = array[i];
            while (cur != null) {
                int hash = cur.key.hashCode();
                int newIndex = hash % newArray.length;
                Node<K, V> curN = cur.next;
                //尾插：
                cur.next = newArray[newIndex];
                newArray[newIndex] = cur;
                cur = curN;
            }
        }
        array = newArray;
    }

    private double doLoadFactor() {
        return this.usedSize * 1.0 / array.length;
    }

    public V getVal(K key) {
        int hash = key.hashCode();
        int index = hash % array.length;
        Node<K, V> cur = array[index];
        while (cur != null) {
            if(cur.key.equals(key)) {
                return cur.val;
            }
            cur = cur.next;
        }
        return null;
    }
}
